1. Field of The Invention
The invention relates to transitions between microstrip and stripline transmission lines and more particularly to a transition that permits easy, solderless disconnection.
2. Prior Art
In high frequency circuits both microstrip and stripline transmission lines are in common use. Each has its place because of its special advantages and both are economical and susceptible to automated fabrication.
The microstrip transmission line is preferable in circuits requiring active components or the inclusion of monolithically integrated circuits in a hybrid mode of assembly. In such applications the provision of a circuit disposed on a dielectric layer over a single ground plane, provides efficient and convenient interconnection. On the other hand, the use of a stripline including a second dielectric and a second ground plane, covering such circuit components, in addition to the difficulties in assembly, would preclude access to the circuit components for "in vitro" testing, trimming or circuit repair. Accordingly, the microstrip transmission line with a single ground plane and single dielectric layer has been the conventional selection for active circuits.
Stripline, on the other hand, has found extensive use in passive networks as, for instance, where branching and distribution occurs. In passive networks, conductor runs which are thin and usually of equal thickness are readily formed and supported between the paired dielectric layers and paired ground planes of stripline. The need for trimming and repair is infrequent in such passive circuits, and with little need for access after assembly, the use of a covered construction is not a disadvantage. Stripline construction has, in fact, definite advantages in passive circuits. The circuits are physically protected from damage and electrically shielded. In addition, the isolation between runs is very good allowing for more compact layouts and minimized losses.
The fact that circuits employing stripline and microstrip transmission paths have complementary advantages has tended to bring both into coexistence in the same electronic assemblies. Thus the need has arisen for economical and efficient transitions between stripline and microstrip circuitry. In addition, when the costs of individual circuits become substantial, it is important to have a transition which permits easy connection and disconnection.